Method for producing cycloalkanol and/or cycloalkanone

ABSTRACT

An object of the present invention is to provide a method capable of producing a cycloalkanol and/or a cycloalkanone with a favorable selectivity coefficient by oxidizing a cycloalkane with a favorable conversion ratio. 
     Disclosed is a method for producing a cycloalkanol and/or a cycloalkanone, which comprises oxidizing a cycloalkane with oxygen in the presence of a mesoporous silica which contains at least one transition metal and has been also subjected to contact treatment with an amine and/or ammonia. Preferably, a crystal obtained by mixing a compound containing the metal, a silicon compound, a structure-directing agent and water is subjected to contact treatment with an amine and/or ammonia and then fired to obtain a mesoporous silica, and a cycloalkane is oxidized with oxygen in the presence of the mesoporous silica.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present patent application claims priority under the ParisConvention based on Japanese Patent Application No. 2008-049509 (filedon Feb. 29, 2008), and the entire content of the aforementionedapplication is herein incorporated by reference.

The present invention relates to a method for producing a cycloalkanoland/or a cycloalkanone by oxidizing a cycloalkane with oxygen.

2. Description of the Related Art

In a method for producing a cycloalkanol and/or a cycloalkanone byoxidizing a cycloalkane with oxygen, a method of performing theoxidation reaction using a mesoporous silica containing a certain kindof a metal element as a catalyst has been studied. For example, thereare known a method using a mesoporous silica containing gold(International Publication No. WO 00/03963 pamphlet), a method using amesoporous silica containing cobalt (Applied Catalysis, Netherlands,2005, Vol. 280, pp.175-180, and a method using a mesoporous silicacontaining chromium or vanadium (Korean Journal of ChemicalEngineering), Republic of Korea, 1998, Vol. 15, pp.510-515).

SUMMARY OF THE INVENTION

The above-mentioned conventional methods include unsatisfactory pointsin view of activity and selectivity of a catalyst, namely, a conversionratio of a cycloalkane and a selectivity coefficient of a cycloalkanoland/or a cycloalkanone. Thus, an object of the present invention is toprovide a method capable of producing a cycloalkanol and/or acycloalkanone with a favorable selectivity coefficient by oxidizing acycloalkane with a favorable conversion ratio.

The present inventors have intensively studied and found that the aboveobject can be achieved by performing the above oxidation reaction in thepresence of a mesoporous silica which contains at least one kind of atransition metal and has been also subjected to contact treatment withan amine and/or ammonia. Thus, the present invention has been completed.

The present invention provides a method for producing a cycloalkanoland/or a cycloalkanone, which comprises oxidizing a cycloalkane withoxygen in the presence of a mesoporous silica which contains at leastone transition metal and has been also subjected to contact treatmentwith an amine and/or ammonia.

According to the present invention, a cycloalkanol and/or acycloalkanone can be produced with a favorable selectivity coefficientby oxidizing a cycloalkane with a favorable conversion ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing pore distribution of a mesoporous silicaobtained in Example 1(C).

FIG. 2 is a graph showing pore distribution of a mesoporous silicaobtained in Comparative Example 1(F).

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described in detail. In the presentinvention, corresponding cycloalkanol and/or cycloalkanone are producedby oxidizing a cycloalkane used as a material with oxygen (molecularoxygen) in the presence of a predetermined mesoporous silica.

Examples of the cycloalkane as the material include monocycliccycloalkanes having no substituent on the ring, such as cyclopropane,cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane,cyclodecane, and cyclooctadecane; polycyclic cycloalkanes such asdecalin and adamantane; and cycloalkanes having a substituent on thering, such as methylcyclopentane and methylcyclohexane, and two or morekinds of them can be used, if necessary.

An oxygen-containing gas is usually used as an oxygen source. Thisoxygen-containing gas may be, for example, an air, pure oxygen, or anair or pure oxygen diluted with an inert gas such as nitrogen, argon orhelium. Oxygen enriched air obtained by adding pure oxygen to an air canalso be used.

In the present invention, the above oxidation reaction is performed inthe presence of a mesoporous silica which contains at least one kind ofa transition metal has been also subjected to contact treatment with anamine and/or ammonia. When such a mesoporous silica is used, acycloalkanol and/or a cycloalkanone can be produced with a favorableselectivity coefficient by oxidizing a cycloalkane with a favorableconversion ratio.

Examples of the metal to be contained in the mesoporous silica includetransition metals and are preferably vanadium, chromium, manganese,iron, cobalt, ruthenium and palladium. Of these metals, cobalt ispreferable. If necessary, two or more kinds of these metals may be used.The content of the metal is usually from 0.01 to 20%, preferably from0.05 to 10%, and still more preferably from 0.1 to 5%, in terms of aweight ratio of the metal to the mesoporous silica.

The mesoporous silica in the present invention has a so-calledmesoporous structure containing pores which usually have nearly uniformsize of 2 to 50 nm, and the surface area is usually from about 600 to1,500 m²/g. The metal may be incorporated into a silica frameworkcomposing the mesoporous structure, or may be incorporated into thepores, or may be supported on the surface of the silica framework.Examples of the mesoporous silica include a MCM-41 type mesoporoussilica, a MCM-48 type mesoporous silica, a FSM-16 type mesoporoussilica, a SBA-15 type mesoporous silica and a HMS type mesoporoussilica, of which a MCM-41 type mesoporous silica is preferable. Thepresence or absence of the mesoporous structure can be confirmed by thepresence or absence of a peak 2θ of 0.2 to 4.0° in the measurement ofXRD (X-ray diffraction).

The method for preparing the mesoporous silica in the present inventionwill now be described. The mesoporous silica to be used in the presentinvention may be prepared by obtaining a crystal containing thetransition metal using also a compound containing the transition metalas a raw material when a known production method of a silica having amesoporous structure is conducted, and subjecting the resultant crystalto contact treatment with an amine and/or ammonia; by contacting asilica having a mesoporous structure obtained by a known method with acompound containing the transition metal and then contacting theresultant with an amine and/or ammonia; or by contacting a silica havinga mesoporous structure obtained by a known method with an amine and/orammonia and then contacting the resultant with a compound containing thetransition metal. In particular, for example, a silicon compound, astructure-directing agent and water are mixed and the resultant crystal(silica having a mesoporous structure) is subjected to contact treatmentwith an amine and/or ammonia and then fired to prepare a desiredmesoporous silica. A silica having a mesoporous structure can beprepared by known methods described in Korean Journal of ChemicalEngineering, Republic of Korea, 1998, Vol. 15, pp.510-515, and Nature,U.S.A., 1992, Vol. 359, pp.710-712. For example, the silica can beprepared by mixing a silicon compound such as tetraalkoxysilane, astructure-directing agent such as a quaternary ammonium salt, and water,and optionally heat-treating the mixture to obtain a crystal, followedby filtration and further drying. In the present invention, in order toallow a mesoporous silica to contain a transition metal, a compoundcontaining a transition metal (hereinafter may be referred to as a metalcompound) may be mixed with the silicon compound, thestructure-directing agent and water, or may be supported on the crystal,or may be mixed with supported on a crystal obtained by contacttreatment with an amine and/or ammonia. It is particularly preferable tomix the metal compound with the silicon compound, thestructure-directing agent and water.

Examples of the silicon compound include tetraalkoxysilanes such astetramethoxysilane, tetraethoxysilane, tetrapropoxysilane andtetrabutoxysilane, and two or more kinds of them can be used, ifnecessary.

Examples of structure-directing agent include alkyltrimethylammoniumbromides having 19 to 21 carbon atoms, such ashexadecyltrimethylammoniun bromide, heptadecyltrimethylammoniun bromideand octadecyltrimethylammoniun bromide; alkyltrimethylammonium chlorideshaving 19 to 21 carbon atoms, such as hexadecyltrimethylammoniunchloride, heptadecyltrimethylammoniun chloride andoctadecyltrimethylammoniun chloride; and alkyltrimethylammoniumhydroxides having 19 to 21 carbon atoms, such ashexadecyltrimethylammoniun hydroxide, heptadecyltrimethylammoniunhydroxide and octadecyltrimethylammoniun hydroxide, and two or morekinds of them can be used, if necessary. Of these structure-directingagents, alkyltrimethylammonium bromides are preferable andhexadecyltrimethylammonium bromide is more preferable.

When the silicon compound, the structure-directing agent and water aremixed, ammonia and/or an alcohol are preferably mixed together with themsince a mesoporous silica having a small particle diameter can beobtained. Ammonia may be liquid or gaseous ammonia. Also, ammonia watermay be used. Such an alcohol can be an aliphatic alcohol having about 1to 6 carbon atoms and specific examples thereof include methanol,ethanol, propanol, butanol, pentanol and hexanol. If necessary, two ormore kinds of them can also be used. Of these alcohols, ethanol ispreferable.

The amount of the structure-directing agent used is usually from 0.1 to1.0 mol, and preferably from 0.2 to 0.5 mol, based on 1 mol of thesilicon compound. The amount of water used is usually from 5 to 30 partsby weight, and preferably from 10 to 15 parts by weight, based on 1 partby weight of the tetraalkoxysilane.

The temperature of mixing of the silicon compound, thestructure-directing agent and water is usually from 20 to 200° C., andpreferably from 20 to 150° C. The mixing time is usually from 0.1 to 400hours, and preferably from 1 to 200 hours.

Thus, a silica crystal having a mesoporous structure can be obtained. Inthe present invention, this crystal is fired after subjecting to contacttreatment with an amine and/or ammonia. A mesoporous silica containingpores having a larger size can be prepared by firing after performingthe contact treatment. The contact treatment is preferably applied to acrystal obtained by filtering a suspension, which is obtained by mixingthe silicon compound, the structure-directing agent and water, followedby drying.

The amine as used herein can be usually a primary, secondary or tertiaryamine bonded with an alkyl group having about 1 to 20 carbon atoms. Ofthese amines, a tertiary amine is preferable, and a dimethylalkylaminesuch as dimethyldecylamine and a triakylamine are more preferable.

The amine and/or ammonia may be used for the contact treatment as theyare, or may be used in the form of an aqueous solution. The amount ofthe amine and/or ammonia used is usually from 1 to 1,500 parts byweight, preferably from 5 to 300 parts by weight, and more preferablyfrom 10 to 150 parts by weight, based on 100 parts by weight of thecrystal before subjecting to the contact treatment. The temperature ofthe contact treatment is usually from 0 to 300° C., and preferably from30 to 250° C. The time of the contact treatment is usually from 0.1 to2,000 hours, and preferably from 1 to 200 hours.

In the present invention, filtration, drying and firing are usuallyperformed after performing the contact treatment. Drying is usuallyperformed under a nitrogen atmosphere, and the drying temperature isfrom about 40 to 120° C. and the drying time is from about 2 to 24hours. Firing is usually performed under a nitrogen atmosphere. Thefiring temperature is from 450 to 650° C., and preferably from 500 to600° C., and the firing time is usually from 4 to 12 hours, andpreferably from 6 to 10 hours.

The mesoporous silica of the present invention contains at least onekind of a transition metal and, as described above, in order to allowthe mesoporous silica to contain the metal, the metal compound may bemixed with the silicon compound, the structure-directing agent andwater, or may be supported on a crystal obtained by mixing the siliconcompound, the structure-directing agent and water, or may be supportedon a crystal obtained by contact treatment of the amine and/or ammonia.Specific examples of the method include (1) a method in which the metalcompound such as halide, nitrate, sulfate, carboxylate, oxo acid salt orhydroxide of metal is added when the silicon compound, thestructure-directing agent and water are mixed, (2) a method in which acrystal obtained by mixing the silicon compound, the structure-directingagent and water is impregnated with a solution of the metal compound,and (3) a method in which a crystal obtained by mixing the siliconcompound, the structure-directing agent and water is immersed in asolution of the metal compound thereby adsorbing the metal compound tothe crystal, or metal cations of the metal compound are exchanged bycations of the crystal. The amount of the metal compound used isappropriately adjusted so as to adjust to the above content of themetal.

It is possible to use, as the material of the transition metal, vanadiumcompounds such as vanadium bromide, vanadium chloride, vanadium fluorideand vanadium naphthate; chromium compounds such as chromium chloride,chromium nitrate, chromium sulfate, chromium acetate and chromiumnaphthate; manganese compounds such as manganese bromide, manganesechloride, manganese fluoride, manganese nitrate, manganese ammoniumsulfate, manganese sulfate, manganese acetate and manganese naphthate;iron compounds such as iron bromide, iron chloride, iron fluoride, ironnitrate, iron sulfate, iron acetate and iron naphthate; cobalt compoundssuch as cobalt bromide, cobalt chloride, cobalt fluoride, cobaltnitrate, cobalt sulfate, cobalt acetate and cobalt naphthate; rutheniumcompounds such as ruthenium bromide and ruthenium chloride; andpalladium compounds such as palladium bromide, palladium chloride,palladium nitrate, palladium sulfate and palladium hydroxide. Of thesecompounds, cobalt compounds are preferable.

In the present invention, it is more effective to performing contacttreatment with an organosilicon compounds after firing. Theorganosilicon compound is preferably reacted with the mesoporous silicato bond on the surface, and can be typically represented by thefollowing formula (1):

Si(R¹)_(x)(R²)_(4-x)   (1)

wherein R¹ represents an alkoxy group, a hydroxy group or a halogenatom, R² represents an alkoxy group, an alkyl group, an allyl group, anaryl group or an aralkyl group, and x represents a number of 1 to 3.

Examples of the alkoxy group represented by R¹ and R² include a methoxygroup, an ethoxy group, a propoxy group and a butoxy group, and examplesof the alkyl group represented by R² include a methyl group, an ethylgroup, a propyl group and a butyl group. Examples of the aryl grouprepresented by R² include a phenyl group, a naphthyl group and a tolylgroup, and examples of the aralkyl group represented by R² include abenzyl group and a phenetyl group.

As the organosilicon compound represented by the formula (1), atriakoxyalkylsilane and a tetraalkoxysilane are more preferably used.

The method of subjecting to contact treatment with an organosiliconcompound includes, for example, a method in which a crystal (mesoporoussilica) after firing is immersed in a liquid containing an organosiliconcompound, and a method in which a gas containing an organosiliconcompound is brought into contact with a crystal (mesoporous silica)after firing.

The amount of the organosilicon compound used is usually from 1 to10,000 parts by weight, preferably from 5 to 2,000 parts by weight, andmore preferably from 10 to 1,500 parts by weight, based on 100 parts byweight of the silica before subjecting to the contact treatment.

The temperature of the contact treatment is usually from 0 to 300° C.,and preferably from 30 to 250° C. The time of the contact treatment isusually from 0.1 to 50 hours, and preferably from 1 to 20 hours.

Thus, the desired mesoporous silica can be obtained. Then, a cycloalkaneis oxidized with oxygen in the presence of the mesoporous silica. Theamount of the mesoporous silica used is usually from 0.0001 to 50 partsby weight, and preferably from 0.001 to 10 parts by weight, based on 100parts by weight of the cycloalkane.

The temperature of the oxidation reaction is usually from 0 to 200° C.,and preferably from 50 to 170° C., and the reaction pressure is usuallyfrom 0.01 to 10 MPa, and preferably from 0.1 to 2 MPa. A reactionsolvent can be optionally used and, for example, nitrile solvents suchas acetonitrile or benzonitrile, and carboxylic acid solvents such asacetic acid or propionic acid can be used.

A post-treatment after the oxidation reaction is not specificallylimited and examples thereof include a method in which a catalyst isseparated by filtering the reaction mixture, followed by washing withwater and further distillation. When cycloalkyl hydroperoxidecorresponding to the cycloalkane as the material is contained in thereaction mixture, it can be converted into the objective cycloalkanoland cycloalkanone by an alkali treatment or a reduction treatment.

EXAMPLES

Examples of the present invention will now be described, but are notlimited thereto. Cyclohexane, cyclohexanone, cyclohexanol and cyclohexylhydroperoxide in the reaction solution were analyzed by gaschromatography, and the conversion ratio of cyclohexane as well as eachselectivity coefficient of cyclohexanone, cyclohexanol and cyclohexylhydroperoxide were calculated from the analysis results.

In Examples, pore distribution of a silica (crystal) having a mesoporousstructure was determined by BJH analysis of an adsorption isotherm of avolumetric method at a liquid nitrogen temperature (77 K). The procedurefor the measurement is as follows.

A glass test tube (volume: 4 ml, inner diameter: 6 mm) was set inBELPREP-vacII manufactured by BEL Japan, Inc. and evacuated and, aftertare measuring, about 0.05 g of a powder sample was filled in the testtube. After evacuating the test tube was evacuated again at 150° C. for3 hours using BELPREP-vacII, the test tube was weighed again and a tareweight is subtracted to obtain a true amount of the powder sample. Next,the test tube subjected to a vacuum pretreatment was set in BELPREP-minimanufactured by BEL Japan, Inc. and a volume (dead volume) peculiar toeach test tube was measured and, after measuring a saturated vaporpressure of nitrogen, an adsorption equilibrium pressure was measured.These operations were repeated until a relative pressure as a ratio ofthe adsorption equilibrium pressure to an initial pressure reaches 0.99to obtain an adsorption isotherm. Pore distribution was derived bycalculating a pore diameter and a pore volume from theBarrett-Joyner-Halenda (BJH) theory utilizing capillary condensation ofa nitrogen gas under assumption of a cylindrical pore and then plottinga change in an amount of the pore volume to the pore diameter.

Example 1

(A) Preparation of Silica having Mesoporous Structure

Hexadecyltrimethylammonium bromide (17.59 g) (manufactured by Wako PureChemical Industries, Ltd.), 327.11 g of water, 106.94 g of ethanol(manufactured by Wako Pure Chemical Industries, Ltd.), 33.76 g oftetraethoxysilane (ethyl orthosilicate, manufactured by Wako PureChemical Industries, Ltd.), 119.34 g of 25% ammonia water (manufacturedby Wako Pure Chemical Industries, Ltd.) and 0.0418 g of cobalt(II)acetate tetrahydrate (manufactured by Wako Pure Chemical Industries,Ltd.) were charged in a 1 liter beaker, stirred at room temperature for2 hours and then filtered. The residue was washed with water and thendried at 100° C. for 12 hours to obtain a crystal A.

(B) Contact Treatment with Amine, and Firing

The crystal A (4.27 g) obtained in Example 1(A), 7.91 g ofdimethyldecylamine (manufactured by Tokyo Kasei Kogyo Co., Ltd.) and87.82 g of ultrapure water were charged in a 300 ml beaker and thenstirred at 25° C. for 50 minutes. After transferring to a 200 mlautoclave and standing at 120° C. for 4 days, the resultant mixture wasfiltered. The residue was washed with water and then dried at 100° C.for 12 hours. The residue was fired under an air flow at 550° C. for 7hours to obtain a crystal B. With respect to the crystal B, poredistribution was determined by the method described above. As a result,a peak attributed to the presence of pores having a size of 6 to 8 nmwas observed. The pore distribution is shown in FIG. 1. The ordinate ofFIG. 1 denotes a change in a pore volume (dVp/ddp), whereas, theabscissa denotes a pore diameter (dp [nm]).

(C) Contact Treatment with Trimethoxypropylsilane

The crystal B (1.0 g) obtained in Example 1(B) and 10.0 g oftrimethoxypropylsilane (manufactured by Tokyo Kasei Kogyo Co., Ltd.)were charged in a flask and then stirred under a nitrogen atmosphere at90° C. for 7.5 hours. The resultant mixture was cooled to roomtemperature and ethanol was added, followed by stirring and furtherfiltration. The residue was washed with ethanol, dried under 0.1 Torr(13 Pa) at 40° C. for one hour and then dried at 100° C. to obtain amesoporous silica X.

(D) Evaluation of Reaction

In a 1 liter autoclave, 278 g (3.3 mol) of cyclohexane and 1.0 g of themesoporous silica X obtained in Example 1(C) were charged. Afterincreasing the pressure in the system to 0.93 MPa at room temperatureusing nitrogen and heating to 140° C., the reaction was carried outunder the flow of a gas having an oxygen concentration of 15% by volumefor 7 hours.

Three hours after the beginning of the reaction, the conversion ratio ofcyclohexane was 6.2%, the electivity coefficient of cyclohexanone was30.6%, the electivity coefficient of cyclohexanol was 44.3%, and theelectivity coefficient of cyclohexyl hydroperoxide was 8.7% (totalelectivity coefficient: 83.6%). Five hours after the beginning of thereaction, the conversion ratio of cyclohexane was 8.5%, the electivitycoefficient of cyclohexanone was 34.3%, the electivity coefficient ofcyclohexanol was 40.1%, and the electivity coefficient of cyclohexylhydroperoxide was 7.6% (total electivity coefficient: 82.0%). Sevenhours after the beginning of the reaction (upon completion), theconversion ratio of cyclohexane was 10.7%, the electivity coefficient ofcyclohexanone was 37.4%, the electivity coefficient of cyclohexanol was36.7%, and the electivity coefficient of cyclohexyl hydroperoxide was6.2% (total electivity coefficient: 80.3%).

Comparative Example 1

(E) Preparation of Silica having Mesoporous Structure

Hexadecyltrimethylammonium bromide (17.59 g) manufactured by Wako PureChemical Industries, Ltd.), 327.11 g of water, 106.94 g of ethanol(manufactured by Wako Pure Chemical Industries, Ltd.), 33.76 g oftetraethoxysilane (ethyl orthosilicate, manufactured by Wako PureChemical Industries, Ltd.), 119.34 g of 25% ammonia water (manufacturedby Wako Pure Chemical Industries, Ltd.) and 0.0418 g of cobalt(II)acetate tetrahydrate (manufactured by Wako Pure Chemical Industries,Ltd.) were charged in a 1 liter beaker, stirred at room temperature for2 hours and then filtered. The residue was washed with water, died at100° C. for 12 hours and then fired under an air flow at 550° C. for 7hours to obtain a crystal E. With respect to the crystal E, poredistribution was determined by the method described above. As a result,a peak attributed to the presence of pores having a size of 2 to 3 nmwas observed. The pore distribution is shown in FIG. 2. The ordinate ofFIG. 2 denotes a change in a pore volume (dVp/ddp), whereas, theabscissa denotes a pore diameter (dp [nm]).

(F) Contact Treatment with Trimethoxypropylsilane

The crystal (1.0 g) obtained in Comparative Example 1(E) and 10.0 g oftrimethoxypropylsilane (manufactured by Tokyo Kasei Kogyo Co., Ltd.)were charged in a flask and then stirred under a nitrogen atmosphere at90° C. for 7.5 hours. The resultant mixture was cooled to roomtemperature and ethanol was added, followed by stirring and furtherfiltration. The residue was washed with ethanol, dried under 0.1 Torr(13 Pa) at 40° C. for one hour and then dried at 100° C. to obtain amesoporous silica Y.

(G) Evaluation of Reaction

The same operation was performed, except that the mesoporous silica Yobtained in Comparative Example 1(F) was used in place of the mesoporoussilica X obtained in Example 1(C).

Three hours after the beginning of the reaction, the conversion ratio ofcyclohexane was 6.0%, the electivity coefficient of cyclohexanone was31.8%, the electivity coefficient of cyclohexanol was 41.6%, and theelectivity coefficient of cyclohexyl hydroperoxide was 8.7% (totalelectivity coefficient: 82.1%). Five hours after the beginning of thereaction, the conversion ratio of cyclohexane was 7.6%, the electivitycoefficient of cyclohexanone was 35.1%, the electivity coefficient ofcyclohexanol was 40.9%, and the electivity coefficient of cyclohexylhydroperoxide was 4.1% (total electivity coefficient: 80.1%). Sevenhours after the beginning of the reaction (upon completion), theconversion ratio of cyclohexane was 10.0%, the electivity coefficient ofcyclohexanone was 37.2%, the electivity coefficient of cyclohexanol was36.3%, and the electivity coefficient of cyclohexyl hydroperoxide was4.2% (total electivity coefficient: 77.7%).

The major embodiments and the preferred embodiments of the presentinvention are listed below.

[1] A method for producing a cycloalkanol and/or a cycloalkanone, whichcomprises oxidizing a cycloalkane with oxygen in the presence of amesoporous silica which contains at least one transition metal and hasbeen also subjected to contact treatment with an amine and/or ammonia.

[2] The method according to [1], wherein the mesoporous silica isprepared by mixing a compound containing the metal, a silicon compound,a structure-directing agent and water to obtain a crystal, subjectingthe crystal to contact treatment with an amine and/or ammonia, and thenfiring the resultant.

[3] The method according to [2], wherein the mesoporous silica isprepared by, after firing, subjecting the fired resultant to contacttreatment with an organosilicon compound represented by the formula (1):

Si(R¹)_(x)(R²)_(4-x)   (1)

wherein R¹ represents an alkoxy group, a hydroxy group or a halogenatom, R² represents an alkoxy group, an alkyl group, an allyl group, anaryl group or an aralkyl group, and x represents a number of 1 to 3.

[4] The method according to any one of [1] to [3], wherein themesoporous silica is MCM-41 type mesoporous silica.

[5] The method according to any one of [1] to [4], wherein the metal isat least one metal selected from the group consisting of vanadium,chromium, manganese, iron, cobalt, ruthenium and palladium.

[6] The method according to any one of [1] to [4], wherein the metal iscobalt.

[7] The method according to any one of [1] to [6], wherein thecycloalkane is cyclohexane.

1. A method for producing a cycloalkanol and/or a cycloalkanone, which comprises oxidizing a cycloalkane with oxygen in the presence of a mesoporous silica which contains at least one transition metal and has been also subjected to contact treatment with an amine and/or ammonia.
 2. The method according to claim 1, wherein the mesoporous silica is prepared by mixing a compound containing the metal, a silicon compound, a structure-directing agent and water to obtain a crystal, subjecting the crystal to contact treatment with an amine and/or ammonia, and then firing the resultant.
 3. The method according to claim 2, wherein the mesoporous silica is prepared by, after firing, subjecting the fired resultant to contact treatment with an organosilicon compound represented by the formula (1): Si(R¹)_(x)(R²)_(4-x)   (1) wherein R¹ represents an alkoxy group, a hydroxy group or a halogen atom, R² represents an alkoxy group, an alkyl group, an allyl group, an aryl group or an aralkyl group, and x represents a number of 1 to
 3. 4. The method according to any one of claims 1 to 3, wherein the mesoporous silica is MCM-41 type mesoporous silica.
 5. The method according to any one of claims 1 to 3, wherein the metal is at least one metal selected from the group consisting of vanadium, chromium, manganese, iron, cobalt, ruthenium and palladium.
 6. The method according to any one of claims 1 to 3, wherein the metal is cobalt.
 7. The method according to any one of claims 1 to 3, wherein the cycloalkane is cyclohexane. 